module.exports = (sql,params) => {
    const mysql = require('mysql');
    const conn = mysql.createConnection({
    host: 'localhost',
    port: 3306,
    user: 'root',
    password: 'root',
    database: 'bigEvent'
});

return new Promise((resolve,reject) => {
    conn.connect();

    conn.query(sql,params,(err,result) => {
        err ? reject(err) : resolve(result)
    });

    conn.end();
}).catch(err => console.log(err.sqlMessage))
//这里输出 err.message 也可以
}